The invention relates to a vacuum cleaner for cleaning floors or carpets, having a suction mouth, a base plate, which encloses the suction mouth, and a suction line, electrostatic charging of parts of the vacuum cleaner being provided in order to assist the dust intake.
In order to assist the cleaning performance of a vacuum cleaner in an effective manner, it is known to utilize electrostatic forces. By separating non-conductive/poorly conductive components of the vacuum cleaner from an object to be cleaned, the two components come to be electrostatically charged. The level and also the polarity are governed by the individual material pairings. Materials such as polyamide, wool or silk serve as donors and give up electrons easily. Separation results in a positive change on these materials. The substances released from these fibres or materials are negatively charged as a result of the electron uptake. An attraction force in the direction of the floor/carpet acts on the oppositely charged particles, the charge being reversed in the case of carpets made of alternative materials, e.g. polypropylene. However, the effects described are still present. If, then, an element, for example a nozzle, of a vacuum cleaner which is more strongly charged than a dust particle of the carpet, is brought into the vicinity of the carpet/dust system, then the attraction force of this element on the charged, floating particle may be sufficiently great, as a result of which the particle is removed. A basic consideration of the bonding forces between a particle and a surface show that essentially three different types of forces are active: the so-called van der Waals forces, the electrostatic forces (contact potential and reflective force) and the capillary forces. In terms of the charge of particles and the transportation thereof in an electric field, it is possible to distinguish between the basic mechanisms of friction, induction, corona discharge and dielectrophoresis.
The prior art utilizes, for example, the electrostatic bonding forces for the deposition of the particles located in an air volume-flow. For this purpose, the particles, which are taken up in the conventional manner by suction, are charged differently and separated by a filter system. Furthermore, a vacuum cleaner is known for example from DE-A1 196 44 589 which has a dust-attracting grid in the region of the suction mouth. The grid is connected to a high-voltage source and is connected up in the manner of a precipitation electrode. The suction-airstream laden with dust particles can flow through the dust-attracting grid.
In relation to the above-described prior-art, a technical problem of the invention is seen in advantageously developing a vacuum cleaner of the type in question in terms of the dust uptake being assisted by electrostatic charging.